Cardiac valve commissure brace

ABSTRACT

A brace for mounting to an annulus of a cardiac valve, the brace comprising: first and second bottom gripping wings for gripping the annulus; first and second top gripping wings for gripping the annulus; and a support bridge that connects the top wings to the bottom wings; wherein the brace is formed from a shape memory alloy and is deformable from a delivery configuration to a deployed configuration and in the delivery configuration the top wings are oriented substantially back to back along an axis and the bottom wings are oriented substantially back to back along the same axis, and in the deployed configuration the first top and first bottom gripping wings face each other to grip the annulus between them and the second top and second bottom gripping wings face each other to grip the annulus between them.

RELATED APPLICATIONS

The present application is a Divisional of co-pending U.S. applicationSer. No. 14/772,394 filed on Sep. 3, 2015, which is a US National Phaseof PCT Application No. PCT/IB2014/059435, filed on Mar. 4, 2014 claimingthe benefit under 35 U.S.C. 119(e) of U.S. Provisional Application61/772,212 filed on Mar. 4, 2013, the disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

Embodiments of the invention relate to devices and instruments forimplementing cardiac valve corrective surgery.

BACKGROUND

The human heart, and generally all mammalian hearts, comprises two bloodpumps that operate in synchrony to oxygenate and deliver oxygenatedblood to the body. A first pump receives deoxygenated blood after it hascoursed through blood vessels in the circulatory system to deliveroxygen and nutrients to the various parts the body, and pumps thedeoxygenated blood through the lungs to be oxygenated. The second pumpreceives the oxygenated blood from the lungs and pumps it to flowthrough the blood vessels of the circulatory system and deliver oxygenand nutrients to the body parts. The two pumps are located adjacent eachother in the heart and each pump comprises two chambers, an atrium thatreceives blood and a ventricle that pumps blood.

The first pump, which receives deoxygenated blood to be pumped to thelungs, is located on the right side of the heart and its atrium andventricle are accordingly referred to as the right atrium and rightventricle. The second pump, which receives oxygenated blood to be pumpedto the body, is located on the left side of the heart and its atrium andventricle are referred to as the right atrium and right ventricle of theheart. The right and left atria are separated by a wall in the heartreferred to as the interatrial septum and the right and left ventriclesare separated by a wall in the heart referred to as the interventricularseptum.

Deoxygenated blood enters the right atrium via blood vessels referred toas the superior vena cava and inferior vena cava. During a part of theheart cycle referred to as diastole the right ventricle is relaxed andthe deoxygenated blood in the right atrium flows from the right atriuminto the right ventricle via a valve, referred to as a tricuspid valve,which connects the right atrium to the right ventricle. The rightventricle contracts during a part of the heart cycle referred to assystole, to pump the deoxygenated blood that it receives from the rightatrium out of the ventricle and into the pulmonary artery via a valvereferred to as the pulmonary valve, which interfaces the pulmonaryartery with the right ventricle. The pulmonary artery delivers thedeoxygenated blood to the lungs for oxygenation. The tricuspid andpulmonary valves control direction of blood flow in the right side ofthe heart. The tricuspid valve opens to let deoxygenated blood flow fromthe right atrium into the right ventricle and closes to preventdeoxygenated blood from regurgitating into the right atrium when theright ventricle contracts. The pulmonary valve opens to let blood enterthe pulmonary artery when the right ventricle contracts and closes toprevent blood regurgitating into the right ventricle when the rightventricle relaxes to receive blood from the right atrium.

The left atrium receives oxygenated blood from the lungs via pulmonaryveins. Oxygenated blood flows from the left atrium into the leftventricle during diastole via a bileaflet valve referred to as themitral valve, which opens during diastole to allow blood flow from theleft atrium to the left ventricle. The left ventricle contracts duringsystole to pump the oxygenated blood that it receives from the leftatrium out of the heart through the aortic valve and into the aorta, fordelivery to the body. The mitral valve operates to prevent regurgitationof oxygenated blood from the left ventricle to the left atrium when theleft ventricle contracts to pump oxygenated blood into the aorta. Theaortic valve closes to prevent blood from regurgitating into the leftventricle when the left ventricle relaxes to receive blood from the leftatrium.

Each valve comprises a set of matching “flaps”, also referred to as“leaflets” or “cusps”. that are mounted to and extend from a supportingstructure of fibrous tissue. The supporting structure has a shapereminiscent of an annulus and is often conventionally referred to as theannulus of the valve. The leaflets are configured to align and overlapeach other, or coapt, along free edges of the leaflets to close thevalve. The valve opens when the leaflets are pushed away from each otherand their free edges part. The aortic, pulmonary, and tricuspid valvescomprise three leaflets. The mitral valve comprises two leaflets.

The leaflets in a valve open and close in response to a gradient inblood pressure across the valve generated by a difference between bloodpressure on opposite sides of the valve. When the gradient is negativein a “downstream flow” or antegrade direction, in which direction thevalve is intended to enable blood flow, the leaflets are pushed apart inthe downstream, antegrade direction by the pressure gradient, and thevalve opens. When the gradient is positive in the downstream direction,the leaflets are pushed together in the upstream or retrograde directionso that their respective edges meet to align and coapt, and the valvecloses.

For example, the leaflets in the mitral valve are pushed apart duringdiastole to open the mitral valve and allow blood flow from the leftatrium into the left ventricle when pressure in the left atrium isgreater than pressure in the left ventricle. The leaflets in the mitralvalve are pushed together so that their edges coapt to close the valveduring systole when pressure in the left ventricle is greater thanpressure in the left atrium to prevent regurgitation of blood into theleft atrium.

Each valve is configured to prevent misalignment or prolapse of itsleaflets as a result of positive pressure gradients pushing the leafletsupstream past a region in which the leaflets properly align and coapt toclose the valve. A construction of fibrous tissue in the leaflets of thepulmonary and aortic valves operates to prevent prolapse of the leafletsin the pulmonary and aortic valves. A configuration of cord-liketendons, referred to as chordae tendineae, connected to muscularprotrusions, referred to as papillary muscles, that project from theleft ventricle wall, tie the leaflets of the mitral valve to the wallsof the left ventricle. The chordae tendineae provide dynamic anchoringof the mitral valve leaflets to the left ventricle wall that operate tolimit upstream motion of the leaflets and prevent their prolapse intothe left atrium during systole. Similarly, a configuration of chordaetendineae and papillary muscles cooperate to prevent prolapse of thetricuspid valve leaflets into the right atrium.

Efficient cardiac valve function can be complex and a cardiac valve maybecome compromised by disease or injury to an extent that warrantssurgical intervention to effect its repair or replacement. For example,normal mitral valve opening and closing and prevention of regurgitationof blood from the left ventricle into the left atrium is dependent oncoordinated temporal cooperation of the mitral leaflets, the mitralannulus, the chordae, papillary muscles, left ventricle, and leftatrium. Malfunction of any of these components of a person's heart maylead to mitral valve dysfunction and regurgitation that warrantssurgical intervention to provide the person with an acceptable state ofhealth and quality of life.

SUMMARY

An aspect of an embodiment of the invention relates to providing astructure and procedures for emplacing and securing the structure to anannulus of a cardiac valve that may operate to improve functioning ofthe valve, and/or provide structural support for apparatus that operatesto improve functioning of the valve. According to an aspect of anembodiment of the invention, the structure, hereinafter also referred toas an “annular brace” or a “brace”, is configured to grip and anchor toan annulus of a cardiac valve in a region of a commissure of the valve.

In an embodiment of the invention, the annular brace comprises first andsecond bottom gripping wings and first and second top gripping wings forgripping and anchoring to the annulus of the cardiac valve in a regionof the commissure. The top gripping wings are connected to the bottomgripping wings by a support bridge. The annular brace has a deliveryconfiguration and a deployed configuration, and is formed from asuitable deformable biocompatible material so that the brace isdeformable from the delivery configuration to the deployedconfiguration. Optionally, the deformable biocompatible material is ashape memory alloy such as nitinol. In the delivery configuration theshape memory alloy brace may be in a martensite state and in thedeployed configuration the material may be in an austenite state.

In the delivery configuration the first and second bottom gripping wingsare folded to lie substantially back to back along a same axis and thefirst and second top gripping wings are folded to lie substantially backto back along the same axis along which the bottom gripping wings lie.In the deployed configuration, the first top and first bottom grippingwings oppose each other to grip a first region of the annulus betweenthem, and the second top and second bottom gripping wings oppose eachother to grip a second region of the annulus between them. The grippingwings are shaped to conform to the curvature of the annular regions thatthey grip. The first and second regions of the annulus lie on oppositesides of the commissure.

A deployment catheter houses the brace in the delivery configuration fordelivery to and for positioning the brace for deployment at the cardiacvalve. Following delivery and positioning at the commissure, thedeployment catheter is controlled to release the annular brace so thatthe brace may deform to the deployed state and grip and anchor to theannulus.

In an embodiment of the invention, the top and bottom first grippingwings are integral portions of a same first “gripping strip” of anelastically deformable biocompatible material and the top and bottomsecond gripping wings are integral portions of a second gripping stripof an elastically deformable biocompatible material. A bridge portion ofthe first gripping strip located between the first gripping strip's topand bottom wings is connected to a bridge portion of the second grippingstrip located between the second gripping strip's top and bottomgripping wings to form the bridge connecting both top wings to bothbottom wings.

In the delivery configuration of the annular brace, the strips are flatand lie substantially back to back. In the deployed configuration thestrips are bent so that the top and bottom wings of the first strip faceeach other to grip the first region of the annulus and the top andbottom wings of the second strip face each other to grip the secondregion of the annulus. The deployment catheter that houses the brace fordelivery to the annulus optionally constrains the brace to the brace'sdelivery configuration. Upon release from the deployment catheter, thebrace, optionally, self deforms to the brace's deployed configuration.

In an embodiment of the invention the first and second gripping stripsare separate strips and their respective bridge portions are connectedusing any of various suitable joining process, such as bonding, gluing,welding, or brazing. Optionally, the first and second gripping stripsand the bridge are integral parts of a same piece, hereinafter alsoreferred to as a “die-shape”, of material shaped by a process such as byway of example, stamping or laser cutting from a sheet of an elasticallydeformable biocompatible material. Suitably bending the die-shapedeforms the die-shape to the delivery configuration of the brace.

In an embodiment of the invention, the annular brace comprises awireform that is bent to provide the first and second top and bottomwings. Optionally, the wireform is cut or stamped from a sheet of anelastically deformable biocompatible material.

In an embodiment of the invention an annular brace is mounted to theannulus of a cardiac valve of a patient at a region of each commissureof the valve to treat compromised performance of the valve. Leafletrestraining struts may be mounted to the braces on the atrial side ofthe valve to constrain motion of the valve leaflets and improveperformance of the valve. In an embodiment of the invention the valvemay be the mitral or tricuspid valve and the restraining struts aremounted to the atrial side of the valve to prevent prolapse of the leafsinto the left or right atrium respectively.

There is therefore provided in accordance with an embodiment of theinvention, a brace for mounting to an annulus of a cardiac valve, thebrace comprising: first and second bottom gripping wings for grippingthe annulus; first and second top gripping wings for gripping theannulus; and a support bridge that connects the top wings to the bottomwings; wherein the brace is deformable from a delivery configuration toa deployed configuration and in the delivery configuration the top wingsare oriented substantially back to back along an axis and the bottomwings are oriented substantially back to back along the same axis, andin the deployed configuration the first top and bottom gripping wingsface each other to grip the annulus between them and the second top andbottom gripping wings face each other to grip the annulus between them.

In an embodiment of the invention, the first top and first bottomgripping wings are integral parts of a same first strip of materialseparated by a bridge portion of the first strip. Optionally, the secondtop and second bottom gripping wings are integral parts of a same secondstrip of material separated by a bridge portion of the second strip.

In an embodiment of the invention, the first top and second top grippingwings are integral parts of a same first strip of material separated bya bridge portion of the first strip. Optionally, the first bottom andsecond bottom gripping wings are integral parts of a same second stripof material separated by a bridge portion of the second strip.

In an embodiment of the invention, the first and second strips ofmaterial are separate strips that are joined by connecting the bridgeportion of the first strip to the bridge portion of the second strip toform the bridge.

In an embodiment of the invention, the first and second strips ofmaterial are integral parts of a same flat piece of material that isbent in a region of the piece of material connecting the bridgingregions of the first and second strips to form the bridge.

The brace may comprise at least one anchor tooth on at least one or moreof the gripping wings that penetrates into the annulus when the brace ismounted to the annulus.

The first top gripping wing may comprise a stabilizer tooth that facesthe first bottom gripping wing to grip the annulus between thestabilizer tooth and first bottom gripping wing prior to completion ofmounting the brace to the annulus.

In an embodiment of the invention, the brace comprises a wireform havingfirst and second wire-loops connected by the support bridge. Optionally,the support bridge comprises at least one wire segment.

In an embodiment of the invention, the first top and first bottomgripping wings are wireform gripping wings comprised in the firstwire-loop.

In an embodiment of the invention, the second top and second bottomgripping wings are wireform gripping wings that are comprised in thesecond wire-loop.

In an embodiment of the invention, the first and second top grippingwings are wireform gripping wings comprised in the first wire-loop. Inan embodiment of the invention, the first and second bottom grippingwings are wireform gripping wings comprised in the second wire-loop.

In an embodiment of the invention, the brace is formed from a shapememory material, and in the delivery configuration the material is in amartensite state and in the deployed configuration the material is in anaustenite state.

There is further provided in accordance with an embodiment of theinvention apparatus for treating prolapse of a leaflet of a cardiacvalve comprising an annulus that supports at least two leaflets thatmeet at least two commissures, the apparatus comprising: a first braceaccording to any of the preceding claims configured to be mounted to theannulus in a region of a first commissure of the at least twocommissures; a second brace according to any of the preceding claimsconfigured to be mounted to the annulus in a region of a secondcommissure of the at least two commissures; and at least one restrainingstrut mountable to the first and second braces after the braces aremounted to the annulus.

In the discussion, unless otherwise stated, adjectives such as“substantially” and “about” modifying a condition or relationshipcharacteristic of a feature or features of an embodiment of theinvention, are understood to mean that the condition or characteristicis defined to within tolerances that are acceptable for operation of theembodiment for an application for which it is intended. Unless otherwiseindicated, the word “or” in the description and claims is considered tobe the inclusive “or” rather than the exclusive or, and indicates atleast one of, or any combination of items it conjoins.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF FIGURES

Non-limiting examples of embodiments of the invention are describedbelow with reference to figures attached hereto that are listedfollowing this paragraph. Identical features that appear in more thanone figure are generally labeled with a same label in all the figures inwhich they appear. A label labeling an icon representing a given featureof an embodiment of the invention in a figure may be used to referencethe given feature. Dimensions of features shown in the figures arechosen for convenience and clarity of presentation and are notnecessarily shown to scale.

FIG. 1 schematically shows a cross section of a human heart thatdisplays the heart chambers and cardiac valves;

FIG. 2A schematically shows a cutaway perspective view of a human heartthat provides a perception of the three dimensional structure of themitral and tricuspid valves of the heart;

FIG. 2B schematically shows the cutaway perspective view of a humanheart similar to that shown in FIG. 2A with the anterior leaflet of themitral valve cutaway for convenience of presentation;

FIG. 3 schematically shows an annular brace mounted to the annulus ofthe mitral valve shown in FIG. 2B, in accordance with an embodiment ofthe invention;

FIGS. 4A-4C schematically illustrate construction of the annular braceshown deployed in FIG. 3, in accordance with an embodiment of theinvention;

FIGS. 4D and 4E schematically show variations of annular braces similarto the annular brace shown in FIGS. 3 and 4A-4C, in accordance with anembodiment of the invention;

FIGS. 4F-4H schematically show stages in deployment of the brace shownin FIG. 3, in accordance with an embodiment of the invention;

FIG. 4I schematically shows an annular brace having stabilizer teeththat function to facilitate stabilization of deployment of an annularbrace during deployment, in accordance with an embodiment of theinvention;

FIGS. 5A-5D schematically illustrate a transseptal deployment of theannular brace shown in FIGS. 3 and 4A-4G, in accordance with anembodiment of the invention;

FIG. 6 schematically shows a view from the atrial side of a mitral valvehaving an annular brace mounted at each commissure of the valve andleaflet restraining struts mounted to the braces, in accordance with anembodiment of the invention; and

FIGS. 7A-7D schematically show a wireframe annular brace, in accordancewith an embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 shows a schematic, stylized cross section of a human heart 20having a right atrium 31 and a right ventricle 32 that communicate via atricuspid valve 33 and a left atrium 41 and left ventricle 42 thatcommunicate via a mitral valve 43. Tricuspid valve 33 has three leaflets34, only two of which are shown in FIG. 1, that are tied by chordaetendineae 35 and papillary muscles 36 to the wall 37 of the rightventricle. Right ventricle 32 communicates with the pulmonary artery 38via the pulmonary valve 39. Mitral valve 43 has two leaflets, anteriorand posterior leaflets 44 (anterior leaflet 44 is in continuity with thewall of the aorta) and 45 respectively that are supported and extendfrom the mitral annulus 46. Mitral valve leaflets 44 and 45 arerespectively tied by chordae tendineae 47 and papillary muscles 48 tothe ventricle wall 49. The left ventricle communicates with the aorta 50via the aortic valve 51.

Deoxygenated blood returning from parts of the body enters right atrium31 and passes through tricuspid valve 33 to enter right ventricle 32during diastole when leaflets 34 of the tricuspid valve are separated(as schematically shown in FIG. 1) to open the tricuspid valve and theright ventricle is relaxed. Flow of deoxygenated blood into the rightatrium via the inferior vena cava 30 and through tricuspid valve 33 intothe right ventricle is schematically indicated by dashed line blockarrows 61. During systole right ventricle 32 contracts to pump thedeoxygenated blood through pulmonary valve 39 and into pulmonary artery38 for delivery to the lungs. During systole leaflets 34 of tricuspidvalve 33 coapt and the tricuspid valve 33 closes to prevent deoxygenatedblood pumped by the right ventricle from regurgitating into the rightatrium. Flow of deoxygenated blood pumped by right ventricle 32 intopulmonary artery 38 is schematically indicated by solid line block arrow62.

Oxygenated blood from the lungs enters left atrium 41 and passes throughmitral valve 43 to enter left ventricle 42 during diastole when leaflets44 and 45 are separated (as shown in FIG. 1) to open the mitral valveand the left ventricle is relaxed. Flow of oxygenated blood into theleft atrium and through mitral valve 43 into the left ventricle isschematically indicated by dashed block arrows 71. During systole leftventricle 42 contracts to pump the oxygenated blood through the aorticvalve 51 and into the aorta 50 for delivery to the body. During systoleleaflets 44 and 45 coapt to close mitral valve 43 and prevent oxygenatedblood pumped by the left ventricle from regurgitating into the leftatrium.

Valves 33, 39, 43, and 51 operate to direct flow of blood in the heartand out from the heart and their proper and efficient function arerequired to maintain a person's health and quality of life. Variousdifferent disease processes may result in damage to a heart valve andcompromise valve functioning. For example, functioning of the mitralvalve may be compromised by various degrees of stenosis, calcification,distortion of the mitral valve annulus, torn chordae tendineae, andfaulty left ventricle functioning. Valve dysfunction and concomitantregurgitation may become so severe as to warrant surgical interventionto provide a person with an acceptable state of health and quality oflife.

FIG. 2A schematically shows a cutaway perspective view of a human heart20 that provides a perception of the three dimensional structure ofmitral valve 43 and tricuspid valve 33. In the figure, a portion ofannulus 46 of mitral valve 43 that supports mitral valve anterior andposterior leaflets 44 and 45 is shown shaded, and a region of acommissure 46-C at which the leaflets come together is indicated. Forconvenience of presentation and the discussion that follows, FIG. 2Bschematically shows heart 20 in which anterior leaflet 44 shown in FIG.2A is cutaway substantially to annulus 46, and chordae tendineae 47 thatconnect the anterior leaflet to papillary muscles 48 are removed.

FIG. 3 schematically shows an annular brace 100 mounted to annulus 46 inthe region of commissure 46-C in accordance with an embodiment of theinvention. Annular brace 100 comprises first and second top grippingwings 101 and 102 and first and second bottom gripping wings 103 and104. In the perspective of FIG. 3 bottom gripping wing 104 is hidden byposterior leaflet 45 and is not shown. Top gripping wings 101 and 102are joined to bottom gripping wings 103 and 104 by a bridge 105.Optionally, top gripping wings 101 and 102 are formed having mountingholes 110 for mounting apparatus to annular brace 100 that a medicalpractitioner may determine to be advantageous for ameliorating a mitralvalve dysfunction.

FIGS. 4A-4H schematically illustrate construction and stages in adeployment of annular brace 100 shown in FIG. 3, in accordance with anembodiment of the invention. Brace 100 is optionally formed from aplanar die-shape 90, schematically shown in FIG. 4A. The die-shapeoptionally comprises a gripping strip 91 having top and bottom grippingwings 101 and 103 respectively connected by a bridging portion 93-1, anda gripping strip 92 having bottom gripping wings 102 and 104respectively that are connected by a bridging portion 93-2. A bridgingregion 93 connects gripping strips 91 and 92. Optionally, die-shape 90is “scalloped” to produce recesses 106 in which annulus 46 seats whenbrace 100 is fully deployed as shown in FIG. 3. A dashed line 94 ondie-shape 90 indicates a fold line along which bridging region 93 isfolded to form bridge 105 (FIG. 3). Folding bridging region 93 alongfold line 94 produces annular brace 100 in the brace's deliveryconfiguration as schematically shown in FIG. 4B. Dashed lines 95 shownin FIGS. 4A and 4B indicate bend lines along which gripping wings101-104 bend to deform brace 100 from the delivery configuration of thebrace to the deployed configuration of the brace in which the bracegrips annulus 46, as shown in FIG. 3. FIG. 4C shows annular brace 100 asit appears in the deployed configuration, without annulus 46.

It is noted, as shown in FIGS. 3 and 4C, that in the deployed state,gripping wings 101-104 not only bend along bend lines 95 but alsooptionally deform to conform to a curvature of annulus 46 at thelocation of commissure 46-C at which the brace is deployed. In anembodiment of the invention, to enable sufficient curvature of top andbottom gripping wings 101-104 to conform to curvature of a cardiac valveannulus, such as annulus 46 of mitral valve 43 or an annulus of atricuspid valve, to which an annular brace, similar to annular brace100, is mounted, the gripping wings may be slotted. Optionally, tofacilitate anchoring brace 100 to the cardiac valve annulus, a grippingwing of the brace is formed having an anchor tooth that bites into theannulus when the gripping wing is deployed. In an embodiment of theinvention, each wing of the annular brace is fitted, optionally at anend of the gripping wing, with at least one anchor tooth. By way ofexample FIG. 4D schematically shows an annular brace 120 similar toannular brace 100, in which gripping wings 101-104 are formed havingslots 122 that facilitate curving of the gripping wings to conform tocurvature of a cardiac valve annulus. Each wing 101-104 comprises ananchoring tooth 124 at an end of the wing.

Die-shape 90 (FIG. 4A) may be produced by way of example, by sintering,molding, or by cutting or stamping, from a sheet of a suitableelastically deformable material. Optionally, the material is a shapememory material which may be a shape memory alloy, such as nitinol, or ashape memory polymer. In an embodiment of the invention, the shapememory material is in a martensite state when brace 100 is in thedelivery configuration and is in an austenite state when the bracedeforms to the deployed configuration, which is a configuration theshape memory material is conditioned to remember. Any of various methodsknown in the art may be used to condition brace 100 to remember thedeployed configuration. It is noted that a die-shape similar todie-shape 90 may be folded and conditioned to provide an annular brace160 schematically shown in FIG. 4E that is similar to annular braces 100and 120, but in which top gripping wings are gripping wings 102 and 104connected by a bridging region 93-2 and bottom gripping wings aregripping wings 101 and 103 connected by a bridging region 93-1. Topgripping wings 102 and 104 are connected to bottom gripping wings 101and 103 by a support bridge 105.

FIGS. 4F-4I schematically show stages in the delivery of brace 100 tomitral valve 43, in accordance with an embodiment of the invention. InFIG. 4F brace 100 is housed in a deployment catheter 150 schematicallyindicated in dashed lines. Optionally deployment catheter 150 has arectangular or square cross section so that the catheter constrainsbrace 100 to the brace's delivery configuration as long as the brace isconfined by the catheter. Optionally, deployment catheter 150 comprisesa push rod 152 that is controllable to push brace 100 out fromdeployment catheter 150 and deploy the brace at mitral valve 43. FIG. 4Gschematically shows annular brace 100 after push rod 152 has partiallypushed the brace out of deployment catheter 150 to release bottomgripping wings 103 and 104 from the deployment catheter. Upon beingpushed out from deployment catheter 150, and released from confinementby the deployment catheter, bottom gripping wings 103 and 104 bend frombridge 105 away from each other to their deployed orientation asschematically shown in FIG. 4H. Upon push rod 152 pushing annular brace100 completely out of deployment catheter 150, top gripping wings 101and 102 bend to their deployed state as shown in FIG. 4C and gripannulus 46 as shown in FIG. 3.

FIGS. 4F-4I show delivery catheter 150 fitting snugly to brace 100 andconstraining the brace to a delivery configuration in which the braceappears to fit snugly in a rectangular volume. However, in an embodimentof the invention, delivery catheter 150 may have a sufficiently largecross section to allow a brace, similar to brace 100 to be delivered ina delivery configuration that is partially deformed from the deliveryconfiguration shown in FIGS. 4B and 4F to the deployed configurationshown in FIG. 4C.

By way of a numerical example, die shape 90 may have a thickness betweenabout 0.5 mm to about 3 mm, wings 101-104 may lengths between about 5 mmto about 20 mm and widths between about 2 mm and about 5 mm. Deliverycatheter may have an internal diameter up to about 7.5 mm.

In some embodiments of the invention an annular brace similar to annularbrace 100 may have stabilizer teeth that deploy from top gripping wingsas the annular brace is pushed out of deployment catheter 150 afterbottom gripping wings 103 and 104 are deployed and a portion, but notall, of top gripping wings 101 and 102 are released from the deploymentcatheter. The stabilizer teeth aid in maintaining position of theannular brace during deployment of the brace. FIG. 4I schematicallyshows an annular brace 140 having stabilizer teeth 142 deployed on anupper surface of annulus 46 after bottom gripping wings 103 and 104 aredeployed and top gripping wings 101 and 102 are partially extended fromdeployment catheter 150.

FIGS. 5A-5D schematically show a transseptal procedure for deployingannular brace 100 at mitral valve 43, in accordance with an embodimentof the invention. FIG. 5A schematically shows deployment catheter 150after the deployment catheter has been threaded into right atrium 31 viathe inferior vena cava 30 (FIGS. 1-2B) and been delivered through apuncture in the atrial septum (not shown) into the left atrium. In theleft atrium, deployment catheter 150 has been controlled to positionannular brace 100 housed in the catheter for mounting to annulus 46. InFIG. 5A annular brace 100 is housed in catheter 150 as shown in FIG. 4F.In FIG. 5B push rod 152 has been controlled to push annular brace 100out from deployment catheter 150 so that bottom gripping wings 103 and104 protrude between anterior and posterior leaflets 44 and 45 (FIGS. 1and 2A) in a region of commissure 46-C to below the leaflets, and recess106 cups the annulus. The position of bottom gripping wings 103 and 104in FIG. 5B relative to deployment catheter 150 is similar to that shownin FIG. 4G. Having been released from deployment catheter 150, grippingwings 103 and 104 bend apart to their respective deployment locationsunder annulus 46 to the left and right respectively of commissure 46-Cas schematically shown in FIG. 5C. In FIG. 5D push road 152 has pushedannular brace 100 completely out of deployment catheter 150, topgripping wings 101 and 102 have bent to their deployed configurationopposite gripping wings 103 and 104 respectively and deployment catheter150 has been removed from left atrium 41. Top and bottom gripping wings101 and 103 sandwich, grip, and anchor to a region of annulus 46 betweenthem and top to the left of commissure 46-C and bottom gripping wings102 and 104 sandwich, grip, and anchor to a region of annulus 46 betweenthem to the right of commissure 46-C. Annular brace 100 is fullydeployed and mounted to annulus 46 at commissure 46-C.

FIG. 6 schematically shows a view from the atrial side of a mitral valve243 comprising leaflets 244 and 245 that are supported by an annulus 246shown shaded and operate to coapt along a seam 247 that extends betweencommissures 248 and 249. Function of mitral valve 243 is assumed to becompromised by prolapse of leaflets 244 and 245 into the atrium. Toalleviate prolapse, in accordance with an embodiment of the invention,an annular brace 100 is mounted to annulus 246 at each commissure 248and 249 of the valve, and leaflet restraining struts 251 and 252 aremounted to braces 100 to restrain motion of the leaflets into theatrium.

FIGS. 7A-7C schematically illustrate construction of an annularwireframe brace 200, in accordance with an embodiment of the invention.

FIG. 7A schematically shows a wireform “blank” 190 after the wireformhas optionally been cut from a sheet of a suitable deformablebiocompatible material or formed from a wire of such a material, inaccordance with an embodiment of the invention. Wireform blank 190optionally comprises two bridge wires 205 that connect wire-loops 191and 192. Wire-loop 191 comprises top and bottom wire gripping wings 201and 203 respectively. Wire-loop 192 comprises top and bottom wiregripping wings 202 and 204 respectively. Bending wire-loops 191 and 192in regions where the wire-loops meet bridge wires 205 as schematicallyshown in FIG. 7B produces wireframe annular brace 200 in a deliveryconfiguration. FIG. 7C schematically shows wireframe annular brace 200in a deployed configuration. It is noted that wireform blank 190 may befolded and conditioned to provide a wireframe annular brace 220 shown inFIG. 7D in which top wire gripping wings are gripping wings 202 and 204and bottom gripping wings are gripping wings 201 and 203. Wireformannular brace 220 is shown in a deployed configuration in FIG. 7D.

Similarly, to annular brace 100 an annular wire brace in accordance withan embodiment of the invention may be formed having gripping teeth andstabilizer teeth. And whereas wire-loops 191 and 192 are shown as simplewire loops formed from straight wire sections, wire-loops in accordancewith an embodiment of the invention may be formed from wavy wiresections or may comprise a wire mesh.

In the description and claims of the present application, each of theverbs, “comprise” “include” and “have”, and conjugates thereof, are usedto indicate that the object or objects of the verb are not necessarily acomplete listing of components, elements or parts of the subject orsubjects of the verb.

Descriptions of embodiments of the invention in the present applicationare provided by way of example and are not intended to limit the scopeof the invention. The described embodiments comprise different features,not all of which are required in all embodiments of the invention. Someembodiments utilize only some of the features or possible combinationsof the features. Variations of embodiments of the invention that aredescribed, and embodiments of the invention comprising differentcombinations of features noted in the described embodiments, will occurto persons of the art. The scope of the invention is limited only by theclaims.

1. A brace for mounting to an annulus of a cardiac valve, the bracecomprising: first and second bottom gripping wings for gripping theannulus; first and second top gripping wings for gripping the annulus;and a support bridge that connects the top wings to the bottom wings;wherein the brace is formed from a shape memory alloy and is deformablefrom a delivery configuration to a deployed configuration and in thedelivery configuration the top wings are oriented substantially back toback along an axis and the bottom wings are oriented substantially backto back along the same axis, and in the deployed configuration the firsttop and first bottom gripping wings face each other to grip the annulusbetween them and the second top and second bottom gripping wings faceeach other to grip the annulus between them.
 2. The brace according toclaim 1 wherein the brace comprises a wireform having first and secondwire-loops connected by the support bridge.
 3. The brace according toclaim 2 wherein the support bridge comprises at least one wire segment.4. The brace according to claim 2 wherein the first top and first bottomgripping wings are wireform gripping wings comprised in the firstwire-loop.
 5. The brace according to claim 2 wherein the second top andsecond bottom gripping wings are wireform gripping wings that arecomprised in the second wire-loop.
 6. The brace according to claim 2wherein the first and second top gripping wings are wireform grippingwings comprised in the first wire-loop.
 7. The brace according to claim2 wherein the first and second bottom gripping wings are wireformgripping wings comprised in the second wire-loop.
 8. Apparatus fortreating prolapse of a leaflet of a cardiac valve comprising an annulusthat supports at least two leaflets that meet at least two commissures,the apparatus comprising: a first brace according to any of thepreceding claims configured to be mounted to the annulus in a region ofa first commissure of the at least two commissures; a second braceaccording to any of the preceding claims configured to be mounted to theannulus in a region of a second commissure of the at least twocommissures; and at least one restraining strut mountable to the firstand second braces after the braces are mounted to the annulus.